The California Center for Population Research at the University of California-Los Angeles (UCLA), was founded in 1998 and received a five-year Population Research Infrastructure Award (R24) in 2001. The Center has fostered an intellectual home for a diverse and interdisciplinary group of population scientists whose collaborative research is advancing public health, addressing health and health disparities, exploring family, neighborhood, and community effects;addressing social and economic mobility and inequality;monitoring migration and its consequences;and advancing data and methods for population research. CPR supports its researchers with Administrative, Computing, and Information Cores, and with two new research cores, Biodemography and Spatial Demography, and a newly expanded Developmental Infrastructure Core that offers small grants for innovative research and nurtures new population scientists. The cores support almost 50 faculty in community health sciences, economics, epidemiology, geography, gerontology, law, policy studies, psychology, sociology, and statistics. Research and didactic workshops and Working Groups provide intellectual stimulation, introduce new areas, facilitate interdisciplinary inquiry, provide informal training, help integrate the diverse interests and skills of CCPR faculty and students, and create a sense of identification with the Center. A key strength of CCPR is its support of research, especially administrative and data support for projects, which is evident in the astonishing growth of extramural funding. In five years of its first R24, CCPR's direct-cost extramural funding has grown from $5m per year to the current $27m, and from 30 NIH and NSF awards to 71. In total, CCPR faculty affiliates have 110 active extramurally funded grants. CCPR researchers conduct research around the world at sites chosen to test hypotheses that transcend local areas. Support from the R24 allows CCPR to provide services that are critical to this work, ranging from administrative support for application preparation and subcontracting issues to state of the art computing and information services. The new Biodemography and Spatial Demography cores will encourage further integration of biology, health sciences, and geography into population science. Both cores respond to needs faced by ongoing work at CCPR. The addition of their activities to CCPR's current service environment will accelerate the work in these areas. The expanded Developmental Infrastructure Core will help to promote nascent ideas in preparation for pursuing extramural funding, to provide support to scientists relatively new to population studies, and to encourage interdisciplinary collaborations in new areas. In combination the activities of the proposed program will allow CCPR to build further on the considerable momentum it has developed over the past five years.